package com.dzsw.javabase.collection;

import java.util.HashMap;
import java.util.Map;

public class KeyNotExistsSample {

    public static void main(String[] args) {
        Map<String, Object> map = new HashMap<>();
        Object obj = map.get("key");
        if (obj == null) {
            System.out.println("obj is null.");
        } else {
            System.out.println("obj is not null.");
        }
    }
}
